Suppose rowing speed is V km/s.
So, upstream speed = V-2
Downstream speed = V+ 2
Total time is taken 3 h 20 min to cover up and down journey of 5 km.
So, total time = upstream time + downstream time
[tex]3. 3 \ hours = \frac{5 km}{ V- 2} + \frac{5 km}{V+2} \\\\\ 3.3 (V^2-2^2) = 10V\\\\V^2- 4-3V= 0[/tex]
[tex]V^2 -4V+V -4=0 \\\\\ V( V-4) +1 (V-4)=0[/tex]
[tex]V= 4 km/h[/tex] and [tex]V= -1 \ km/h[/tex], we take only positive velocity.
Thus, the the rowing speed of the crew in still water is 1 km/s.
